The prevalence of childhood overweight (CO) has tripled in recent decades and there is growing recognition of environmental factors related to the rapid increase of this significant public health problem. Socio-ecological models provide a strong theoretical framework for studying the interplay between an individual's weight-related behaviors and his or her environment. Data linking built environments to eating and physical activity habits underscore the potential importance of carefully assessing neighborhood-level variables in weight loss clinical trials. However, few studies have examined whether neighborhood environmental characteristics differentially impact an individual's attempt to modify physical activity and eating behaviors. Spatial databases and Geographic Information System (GIS) technologies provide a means for objectively assessing environmental factors that may moderate weight loss maintenance treatment response. Our present R01 is designed to test the efficacy of an enhanced social facilitation maintenance treatment (SFM+) for overweight children and their families. SFM+ is informed by learning theory and involves lengthening maintenance treatment contact and enhancing treatment focus by targeting a broad range of socio-environmental levels for intervention (individual/self-regulatory skills, family involvement and the home environment, peer relationships and social support, and identification of neighborhood or community resources and barriers to healthy lifestyle behaviors). The objective of SFM+ is to strengthen newly developed weight-regulating skills across socio-environmental contexts over time in order to decrease relapse. Overweight children (N=240) and their parents will complete four months of a family-based behavioral weight loss program and will then be randomized to one of three 8- month maintenance conditions: (1) low dose SFM+ [LOW;16 sessions], (2) high dose SFM+ [HIGH;32 sessions], or (3) a credible health education CONTROL [16 sessions] matched on schedule, duration, and attention of the LOW condition. The LOW and HIGH conditions are matched on content and duration, but differ in treatment dose. We hypothesize that the HIGH condition will produce better weight maintenance and greater improvements in associated outcomes than either the LOW or the CONTROL conditions, and that the LOW condition will produce better weight maintenance than the CONTROL condition. The proposed ancillary study will form a transdisciplinary team of scientists including basic behavioral, public health, and urban design to test the exploratory hypothesis that children's built environment will be a moderator of weight loss maintenance treatment. Because HIGH intensively targets the socio-environmental context, we predict that HIGH will prove more effective than either CONTROL or LOW for the subset of children whose community environments provide limited access to healthful food and opportunities for physical activity. This study promises to not only clarify the most efficacious overall treatment choice for CO, but also to identify subgroups for whom specific treatments are indicated, and to inform public health approaches to the long-term management of CO. PUBLIC HEALTH RELEVANCE: This project seeks to strengthen and expand upon the current R01's aim to identify environmental moderators of pediatric weight loss maintenance. The addition of objective measures of the built environment will provide an important opportunity for transdisciplinary collaboration among public health professionals, urban design investigators, and clinical researchers, as well as add to our understanding of the neighborhood-level characteristics that may influence pediatric obesity treatment response. It is necessary to better understand for whom and under what conditions weight loss is maintained, in order to stem the childhood obesity epidemic and to prevent the tracking of obesity and its negative health and psychosocial consequences into adulthood.